Patent GB-762486-A (GB)
Title: Electric converting systems
Inventor: DOUBLE HUGH STANLEY
IPC: H02M7/08
Filed: 1953-09-18
Abstract: 762,486. Rectifying; automatic voltage control systems; supply systems depending on two or more sources. SIEMENS BROS., & CO., Ltd. Dec. 17, 1954 [Sept. 18, 1953], No. 25853/53. Classes 38 (2) and 38 (4). In a rectifier system in which two or more saturable reactor controlled metal rectifiers are operated in parallel, and in which load sharing is effected by windings responsive to the output current of the previous rectifier in the sequence, these windings are on magnetic amplifiers which in turn control the saturable reactors. In one embodiment, Fig. 1 (not shown), two rectifiers, each substantially of the kind disclosed in Specification 608,423, each include an additional current controlled winding on their magnetic amplifiers, these windings being cross-connected to shunts in the rectifier output circuits. In a modification, Fig. 2, one rectifier CC, as in the prior Specification, may be paralleled with a rectifier CD which includes a current winding IV as above by changing over switch CSW to the upper position so that the current-control winding IV is connected in series with the output of rectifier CC, and the voltage control winding II is connected to an auxiliary rectifier BR energized by transformer TRA in accordance with the A.C. input voltage to the main rectifier CD. For non-parallel operation, the lower position of switch CSW connects the voltage winding II to the bridge VSN as in the prior Specification, and short-circuits the current winding IV. In another embodiment, Figs. 3A, 3B, one rectifier acts as a master, and additional slave rectifiers are automatically connected in parallel in succession as the load increases. Only one rectifier MRR is shown as typical of all the series. This is supplied via contactor CLC and is controlled by saturable reactor CHP, CHQ, having a current-control winding II in series with the rectifier, a bias winding IV energized by rectifier ARR from the A.C. supply, and a winding III controlled by the magnetic amplifier CHX, CHY. This amplifier has a winding V responsive to the A.C. input voltage, a feedback winding 111; and, controlled by a change-over switch MSW, a voltage winding II which is connected to an output voltage responsive bridge PDD when the rectifier is selected as "master" or disconnected when it is a " slave," and a current winding IV which as before is connected across a shunt such as SHB in the previous rectifier's output circuit, when acting as "slave". To effect the successive switching of units as the total load varies, a relay coil AMC, controlling change-over contacts cma is connected in series with a resistor SY across a shunt SHA in each individual's output circuit. When the output of the particular rectifier exceeds 80 per cent of the normal rating contacts cma energize a relay OP, which closes contacts op1 to hold in relay AMC and closes contacts op2 to energize coil OPC of the next rectifier (via terminals 7, 8, 12 and contacts ol1 and CPC). Coil OPC closes the main contactor CLC and so energizes the succeeding rectifier. When the output of the first rectifier falls below 70 per cent of normal, contacts cma change over and energize relay TP, which closes contacts tp1 to shunt relay AMC and closes contacts tp2 to trip the contactor CLC of the succeeding rectifier by energizing the trip coil TRP. Coil TRP can also be energized manually by push-button TSW, or by overload relay COL. Specification 627,791 also is referred to.